package chapter.sixth.item36;

import java.util.HashSet;
import java.util.Set;

public class Bigram {
	
	private final char first;
	private final char second;
	
	public Bigram(char first,char second){
		this.first = first;
		this.second = second;
	}
	
	//未覆盖Object类的equals方法
	public boolean equals(Bigram b){
		return b.first == first && b.second == second;
	}
	
	public int hashCode(){
		return 31*first + second;
	}
	
	public static void main(String[] args) {
		Set<Bigram> s = new HashSet<Bigram>();
		for(int i=0; i<10;i++)
			for(char ch = 'a';ch<='z';ch++)
				s.add(new Bigram(ch,ch));
		System.out.println(s.size());//结果为260,而应该是26
	}
}
